Tim x, biet: a, ( x + 1 )^2 + ( x - 2 )^2 = 5 b, x^3 - 3x^2 - x = -3

tim x, biet: a, ( x + 1 )^2 + ( x - 2 )^2 = 5        b, x^3 - 3x^2 - x = -3